Climate and energy

NOTE: Wind Week will have to extend into next week! We just had too much material - in particular, on the environmental impacts of wind power. So stay tuned.

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This past week, a few folks have mentioned Karen Dillon’s recent article in the KCStar, where she looked into possible effects of wind turbines on human health.

Since people seemed to want to know more, CEP did a bit of additional research. Before diving in to our findings, though, we’d just to state our position right up front:

CEP supports the responsible and sustainable development of renewable energy, including wind power. However, we do not think wind turbines should simply go anywhere on the landscape. Clearly, there are places where wind power is not appropriate, and scale should also be carefully considered.

We also recognize that all technologies have benefits and burdens that must be considered. During their life cycle, all technologies have environmental impacts – on air, soil, and water quality, as well as on human health and wildlife. As beneficiaries of technology, it is our obligation to mitigate and/or eliminate these impacts as much as possible.

So, that said. CEP then took a look at the issues on wind power’s impact on human health and wildlife. Some of the most reliable information on this question comes from a recent report by the National Research Council of the National Academies, “Environmental Impacts of Wind Energy Projects.” (You can read it online, but it costs $$ to download.)

HUMAN HEALTH

Major point: So far there is “relatively little dispassionate analysis of the human impacts of wind-energy projects. Much that has been written has been from the vantage points of either proponents or opponents.”

Translated, there’s just not a lot of scientifically objective evidence out there yet, either way. Instead, you have two pretty polarized camps. One side says that the noise from turbines is awful and that shadow flicker will drive you nuts. Etc. The other side more or less says, nope.

Let’s try and stand in the middle for a second.

Frankly, quantifying evidence either way can be pretty tough to measure. Sensitivity to noise and shadow flicker are fairly subjective. They differ from person to person, from place to place, and from wind turbine to wind turbine.

Measuring noise and shadow flicker also depends on many factors - wind speed, flow, and direction, terrain, latitude, sun position, whether there was a pre-construction baseline of noise measured at the site, and so on. All of which makes these phenomena hard to study.

However, according to the NRC report, here is what we do know:

Air quality. By improving air quality, wind energy has positive benefits for human health, especially compared to electricity generated from fossil fuels. There are emissions associated with manufacturing, transporting, and installing turbines (as with any electrical generation), but when operating, wind turbines emit no greenhouse gases or other pollutants like nitrous oxides, sulfur oxide, mercury, etc.

Sound. Sound (noise) from turbine operation comes in three main forms – broadband, tonal, and low-frequency. Improved engineering of large wind turbines has all but eliminated mechanical sounds from gearboxes, etc. Complaints tend to center on the sound of turbine blades interacting with wind. A wind turbine creates sound pressure of 50-60 dB(A) (a decibel measurement) at 40 meters. For comparison, a busy office measures 60 dB(A), and nighttime ambient noise in the countryside (leaf rustles, etc.) measures between 20-40 dB(A).

Vibrations. Generally, the impact of low-frequency vibrations on human health is not well-understood. For example, some people could easily live next door to a subway and never notice the vibrations, but others could not. However, just because the problem is hard to understand doesn’t mean it does not exist.

Shadow flicker. Shadow flicker is caused by turning turbine blades, which create variations in shadow patterns. It is a problem in northern Europe (especially in winter, due to lower sun angles at a higher latitude) but is not considered to be so in the U.S. While it can be annoying, a wind turbine’s flicker frequency (0.6-1.0 Hz) is physically harmless to humans. Only frequencies above 10Hz can cause seizures in humans. Strobe light frequencies are between 3 Hz and 10 Hz.

Lighting. Something the NRC study did not address: the possible effects of wind turbines’ nighttime lighting on human health. Due to FAA regulations, all towers must be lit from dusk to dawn. This could possibly cause poor sleeping patterns for homeowners who live too close. People who live close to cell phone or other communications towers (and there are many more of those than wind turbines) complain about this problem.

Zoning. While the health effects of wind power are not yet known - and may never be known with certainty - zoning and siting guidelines can do a great deal to mitigate the possible annoyance issues. Some counties have addressed these issues. However, most large wind installations go into rural areas, where zoning of any kind is frequently scarce.

So, after reading this - are you now curious about exactly how noisy wind turbines are? Check out the following video.

A caveat - these turbines portrayed in the video are the big, utility scale turbines. Around one megawatt and up. Smaller turbines can be noisier. Lots of research dollars have recently been poured into making the big ones quiet, and keeping them from having an impact on flying wildlife. The same has yet to be consistently done for the smaller turbines.

Of course, because of their scale, smaller turbines are also more likely to be installed close to homes, schools, and businesses.

No easy answers, eh? well, that means it’s a lot like the rest of life.

— Maril Hazlett, www.climateandenergy.org

Other offerings in CEP’s Wind Week so far:

Wind power and human health
Photo essay, Smoky Hills Wind Farm
What you need to know to get started on wind energy
Colby Wind Summit
Wind in the News